A method of this type is known by the name of tomosynthesis. A sequence of x-ray images is taken. In order not to keep taking the same x-ray images the relative position between x-ray source and object is varied in each case. In this case this takes place in such a way that the x-ray source is moved in a straight line. Since in an x-ray source method the x-ray detector is conventionally not large enough to always receive the x-rays which have penetrated the patient's body, the x-ray detector is conventionally also moved in a straight line. The movement in a straight line of x-ray source and x-ray detector is coordinated, i.e. coupled. The x-ray detector can be moved in the same direction as the x-ray source or in the opposite direction thereto. As an alternative to moving at least the x-ray source and optionally also the x-ray detector, the object may also be moved in a straight line. As a rule this is done in such a way that the patient table, on which the patient is situated, is moved. Of course it is also possible for x-ray source/x-ray detector and the object to be moved in a straight line simultaneously.
Computer tomography (CT) is a method that differs from tomosynthesis and one in which a large number of x-ray images is taken. Characteristic of CT is that the image density and the area from which the images are obtained are sufficiently high or great to allow an exact reconstruction of the imaged object by 3D image data within the framework of image resolution. A CT image record can thus be designated complete. Characteristic of tomosynthesis is that the image data is not complete, i.e. that there are basically limitations to the quality of the reconstruction. This is opposed by the advantage of tomosynthesis that considerably fewer x-ray images from a much smaller area are taken overall, whereby tomosynthesis can be carried out much quicker than CT and owing to the smaller area has advantages in terms of patient accessibility.
Said type of tomosynthesis, in which the imaging system or the patient is moved in a straight line, demonstrates drawbacks in resolution quality, in particular in an especially marked direction. This direction is defined by a connecting line between the respective axes of movement in the case of moveable x-ray source and movable x-ray detector. When using a flat-panel x-ray detector this connecting line defines the same direction as the surface normal of the flat-panel x-ray detector.